The objective of this study is to delineate the molecular events involved in the differentiation of the sebaceous cell. Sebocytes will be isolated from mouse preputial glands and separated by making use of the fact that during differentiation the diameter increases about six-fold and the density steadily decreases as lipid accumulates in the cell. Changes in chemical composition, metabolic and enzyme activity throughout differentiation will be mapped out. The effects of hormones on differentiation will be studied, as will that of drugs, chalones and other regulators. In this manner the mode of action of such substances on the sebocyte will be elucidated. Studies will also be made on a murine sebaceous tumor in an effort to identify a metabolic defect responsible for its unrestricted growth. The investigation will subsequently encompass the isolation and study of human sebocytes and the establishment of cell lines in culture. As a result of these studies a model will be developed for the assay of anti-androgens and the study of the mode of action of antilipemic drugs. A simple cytodifferentiating system will become available for general biological study while the data obtained from the investigation will be relevant to our understandng and treatment of acne and to our knowledge of cutaneous carcinogenesis.